meljun cortes os introduction

Operating System → is a program that acts as an intermediary between the user of computer and the

computer hardware.

Operating System → is a set of software routines that sits between the application program and

hardware.

*routines: perform key support functions such as accepting and carrying out user commands, communicating with

peripheral devices, load a program, copy a file and create a directory

Operating System → acts like an interface between the user and computer hardware.

Operating System → is a tool to facilitate efficient operation of computer system

1.0 What is Operating System?

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FOUR COMPONENTS OF FOUR COMPONENTS OF COMPUTER SYSTEMCOMPUTER SYSTEM

1. Hardware –> provides the basic computing resources. (CPU, Memory, I/O Devices)

2. Application Program –> define the ways in which these resources are used to solve the computing problems of the

users. (Compilers, database system, games & business programs)

3. Users –> the one who solve problems in many different application programs. (People and machines)

4. Operating System –> control coordinates the use of hardware among the various application programs for various users.

-> provides environment with other programs to do useful work.

-> allocates resources requested by specific programs users to operate computer system fairly and efficiently.

Computer componentsComputer components

HardwareHardwareSoftwareSoftwarePeople warePeople wareData wareData ware

GOALS OF OPERATING SYSTEMTo make computer system convenient to useTo use the computer hardware efficiently

FUNCTIONS / SERVICES OF OPERATING SYSTEMAs a Service ProviderAs a Resource Manager

OS as a Resource ManagerOS as a Resource Manager

Keeps tracks of its resources.Keeps tracks of its resources.

Allocate and de-allocate resourcesAllocate and de-allocate resources

It enforces policies in the user and with It enforces policies in the user and with the acquisition of resources.the acquisition of resources.

OS as a Service ProviderOS as a Service Provider

Acts as a resource managerActs as a resource managerFile managerFile manager Input/output modules managerInput/output modules managerAccountingAccountingRecovery and archivingRecovery and archivingError detection and correctionError detection and correctionExecute and manipulate filesExecute and manipulate files

Operating System as a Service Provider:Operating System as a Service Provider:

1. Resource Manager* Program execution

The operating system is responsible for the following activities in connection with process management:

the creation and deletion of both user and system processesthe suspension and resumption of processesthe provision of mechanisms for processes synchronizationthe provision of mechanisms for process communicationthe provision of mechanisms for deadlock handling

Operating System as a Service Provider:Operating System as a Service Provider:

2. I/O Manager* involve a file and I/O devices

3. File Managera. Manipulation of Datab. Execution of Datac. Recovery & Archiving

4. Protection & Security*protection involves ensuring that all access to system

resources is controlled, security eventually a password which every user having to authenticate himself to the system.

5. Accounting* To keep track the resources and what kind of computer

resources.

6. Error Detection & Handling*operating system needs constantly be aware

of possible errors.

OS Major ComponentsOS Major Components

Memory managerMemory managerProcessor managerProcessor managerDevice managerDevice managerFile managerFile manager Job schedulerJob scheduler

Criteria to measure OS Criteria to measure OS effectivenesseffectiveness

CostCostReliabilityReliabilityThroughputThroughputResponse timeResponse timeTurn around timeTurn around timeEase of useEase of usesecuritysecurity

CRITERIA TO MEASURE THE CRITERIA TO MEASURE THE EFFECTIVENESS OF THE OSEFFECTIVENESS OF THE OS

1. Throughput --> the amount of work going on a computer system --> measure of work is the number of processes

that are completed per unit time.2. Turnaround Time --> is the sum of the periods spent waiting to

get into memory waiting in the ready queue, executing on the CPU, and doing I/O.

--> elapsed time from the job submission up to job completion.

3. Waiting Time --> is the sum of the periods spent waiting in the ready queue.

4. Response Time --> the amount of time it takes to start responding, but not the the time that it takes

to output that response.5. Availability --> the measures of system accessibility6. Cost 8. Reliability7. Ease of Use 9. Security

HISTORY OF OPERATING SYSTEMHISTORY OF OPERATING SYSTEM0th Generation – 1945 1955

- No OS at all, machines is controlled hard-wired (Punch card). - No existence of O.S only encoding - No protection - Black Box Concept (Human Operators)

*Encoding – programming techniques that binary bit is presented

through voltages.

1st Generation – During 1950’s, simple operating system were developed that allowed programs to be submitted in sequence and stored.

- Batch Processing / Batch Oriented Processing.- Age of Vacuum Tubes

HISTORY OF OPERATING SYSTEMHISTORY OF OPERATING SYSTEM

2nd Generation – During 1960’s Multi-using was developed. - Age of Transistors

*Multi-using:

- To store several programs in memory simultaneously- Share computer resources

3rd Generation – Mid 1960, Multiprocessing, Multiprogramming, Time-Sharing, Real-time processing & Virtual memory were introduced.

- Aged of Integrated Circuits

*Virtual Memory – the ability of OS to expand the memory of computer systems.

HISTORY OF OPERATING SYSTEMHISTORY OF OPERATING SYSTEM4th Generation – the period of Networking System & Distributed O.S that provide networking & communication function.

- Open system were introduced - Interoperability & other network standard - Massive memory was develop (expansion)

*Open System1. Portability –> a system that can be applied in any kind of

computer environment2. Availability –> source-code licenses in short notice3. Scalability –> the code can be transferable and resizable4. Interoperability –> a system that allow sharing of files and

applications.

HISTORY OF OPERATING SYSTEMHISTORY OF OPERATING SYSTEM

5th Generation5th Generation – – Multimode system Multimode system (1980’s)(1980’s)Provide higher resolutionProvide higher resolutionSpeech synthesizers & RecognitionSpeech synthesizers & RecognitionComputer VisionComputer VisionAllow intelligent machines & Open SystemAllow intelligent machines & Open System

**Multimode SystemMultimode System – connotes multi- – connotes multi-processing & multiprogrammingprocessing & multiprogramming

TYPES OF OPERATING TYPES OF OPERATING SYSTEMSSYSTEMS

Single Programmed OS / Single Job Single Programmed OS / Single Job StreamStream

Allows execution of program one at a time.Allows execution of program one at a time. One program activeOne program active

Batched OSBatched OS allowed automatic job sequencing by a allowed automatic job sequencing by a

resident operating system and improved the resident operating system and improved the overall utilization of the computer. The overall utilization of the computer. The computer no longer had to wait for human computer no longer had to wait for human operation.operation.


Batched OSBatched OS The common input devices were card readers & tape drivers.The common input devices were card readers & tape drivers. The common output devices were line printers & card The common output devices were line printers & card

punches.punches. Console: a terminal that consists of switchesConsole: a terminal that consists of switches

A A batch systembatch system was introduced to collect a batch of jobs was introduced to collect a batch of jobs before processing them and printing out results. A batch before processing them and printing out results. A batch system consists of three stages—job collection, job system consists of three stages—job collection, job processing, and printing out results. All three stages can processing, and printing out results. All three stages can occur concurrentlyoccur concurrently

Multi-programmed OSMulti-programmed OS jobs are kept in memory at one timejobs are kept in memory at one time having several programs running concurrently in the having several programs running concurrently in the

computer.computer.


Time-sharing/Multi-tasking/Multi-usingTime-sharing/Multi-tasking/Multi-using Logical extension of multi-programming.Logical extension of multi-programming. Time shared OS: allows many users to share the Time shared OS: allows many users to share the

computer simultaneously. Uses CPU scheduling.computer simultaneously. Uses CPU scheduling. Having several users running in the computer Having several users running in the computer

system.system. Real-time OSReal-time OS

Type of OS that is designed for a particular task Type of OS that is designed for a particular task through the use of sensors.through the use of sensors.

Sensors bring data to the computer.Sensors bring data to the computer. Real system is defined, fixed and time constraint.Real system is defined, fixed and time constraint.


2 FLAVORS OF REAL TIME SYSTEM:2 FLAVORS OF REAL TIME SYSTEM: Hard real-time systemHard real-time system – guarantees that critical – guarantees that critical

task is completed on time.task is completed on time. A hard real-time system is often used as a control device A hard real-time system is often used as a control device

in a dedicated application.in a dedicated application. A hard real-time operating system has well defined, A hard real-time operating system has well defined,

fixed time constraints. Processing must be done within fixed time constraints. Processing must be done within the defined constraints, or the system will fail.the defined constraints, or the system will fail.

Soft real-time systemSoft real-time system – a critical real-time task – a critical real-time task get s priority over other task, and retains that get s priority over other task, and retains that priority until it completes.priority until it completes. Soft real-time systems have less stringent timing Soft real-time systems have less stringent timing

constraints, and do not support deadline scheduling. constraints, and do not support deadline scheduling.


APPLICATION OF REAL-TIME SYSTEMAPPLICATION OF REAL-TIME SYSTEM Satellite CommunicationSatellite Communication RoboticsRobotics Home Appliances ControllersHome Appliances Controllers Nuclear weapon systemNuclear weapon system Scientific Experiment SystemScientific Experiment System Industrial Control SystemIndustrial Control System Automatic-Fuel-Engine-Injection SystemAutomatic-Fuel-Engine-Injection System Imaging/X-raysImaging/X-rays


Distributed OS / Network OSDistributed OS / Network OS Network Operating System is an OS that provide Network Operating System is an OS that provide

features such as file sharing (WIN NT) across the features such as file sharing (WIN NT) across the network, which includes a communication network, which includes a communication scheme that allows different processes on scheme that allows different processes on different computers to exchange messages.different computers to exchange messages.

A distributed system is a collection of processors A distributed system is a collection of processors that do not share memory or a clock. Instead, that do not share memory or a clock. Instead, each processor has its own local memory, and each processor has its own local memory, and the processors communicate with one another the processors communicate with one another through various communication lines, such as through various communication lines, such as high-speed buses or telephone lines.high-speed buses or telephone lines.

A distributed system provides the user with A distributed system provides the user with access to the various resources located at access to the various resources located at remote sites.remote sites.


Distributed OS / Network OSDistributed OS / Network OS Distributed OS is a less autonomous Distributed OS is a less autonomous

environment. The processors in a distributed environment. The processors in a distributed system may vary in size and function. They system may vary in size and function. They may include small microprocessors, may include small microprocessors, workstations, minicomputers, and large workstations, minicomputers, and large general-purpose computer systems. general-purpose computer systems.

VARIETY Of REASONS FOR BUILDING VARIETY Of REASONS FOR BUILDING DISTRIBUTED SYSTMEMS:DISTRIBUTED SYSTMEMS: Resource SharingResource Sharing.. If a number of different If a number of different

sites are connected to one another, then a user sites are connected to one another, then a user at one site may be able to use the resources at one site may be able to use the resources available at another.available at another.


Distributed OS / Network OSDistributed OS / Network OS Computation SpeedupComputation Speedup.. If a particular If a particular

computation can be partitioned into a number of computation can be partitioned into a number of sub computations that can run concurrently, sub computations that can run concurrently, then a distributed system may allow us to then a distributed system may allow us to distribute the computation among the various distribute the computation among the various sites - to run that computation concurrently.sites - to run that computation concurrently.

ReliabilityReliability.. If one site fails in a distributed If one site fails in a distributed system, the remaining sites can potentially system, the remaining sites can potentially continue operating. If the system is composed of continue operating. If the system is composed of a number of large autonomous installations, the a number of large autonomous installations, the failure of one of them should not affect the rest.failure of one of them should not affect the rest.


Distributed OS / Network OSDistributed OS / Network OS CommunicationCommunication.. There are many instances in which There are many instances in which

programs needs to exchange data with one another on one programs needs to exchange data with one another on one system. Example: Users may initiate file transfers or system. Example: Users may initiate file transfers or communicate with one another via electronic mail. A user communicate with one another via electronic mail. A user can send mail to another user at the same site or at a can send mail to another user at the same site or at a different site.different site.

Personal Computer OSPersonal Computer OS - Personal computer - Personal computer systems are microcomputers that are considerably systems are microcomputers that are considerably smaller and less expensive than are mainframe smaller and less expensive than are mainframe systems. Operating system for these computers systems. Operating system for these computers have benefited from the development of operating have benefited from the development of operating systems for mainframes in several ways.systems for mainframes in several ways.

QUIZQUIZ

QUIZQUIZTest 1: IdentificationTest 1: Identification

1. It controls and coordinates the use of hardware 1. It controls and coordinates the use of hardware among the various application program for various among the various application program for various users.users.

2. A program that runs at all times on the computer2. A program that runs at all times on the computer3. It is the ability of Operating System to expand the 3. It is the ability of Operating System to expand the

memory of computer system.memory of computer system.4. A program used for loading at power-up or during 4. A program used for loading at power-up or during

the rebooting process. Typically stored in ROM or the rebooting process. Typically stored in ROM or EPROM, generally known as firmwareEPROM, generally known as firmware

5. It allows execution of programmed one at a time.5. It allows execution of programmed one at a time.6. It provides higher resolution and speech recognition.6. It provides higher resolution and speech recognition.7. Guarantees that the critical task is complete on time.7. Guarantees that the critical task is complete on time.8. A software-generated interrupt caused either by an 8. A software-generated interrupt caused either by an

error or a user request.error or a user request.9. A type of Operating System having several programs 9. A type of Operating System having several programs

running concurrently in the computer.running concurrently in the computer.10. A terminal that composed of switches 10. A terminal that composed of switches

11. A request to the operating system to allow user to 11. A request to the operating system to allow user to wait for I/O completion.wait for I/O completion.

12. It contains entry for each I/O device indicating its type, 12. It contains entry for each I/O device indicating its type, address, and state.address, and state.

13. It is used for high-speed I/O devices able to transmit 13. It is used for high-speed I/O devices able to transmit information at close to memory speeds.information at close to memory speeds.

14. An extension of main memory that provides large 14. An extension of main memory that provides large nonvolatile storage capacity.nonvolatile storage capacity.

15. It determines the logical interaction between the 15. It determines the logical interaction between the device and the computer. device and the computer.

16. A principle of copying information into faster storage 16. A principle of copying information into faster storage system; main memory can be viewed as a last cache for system; main memory can be viewed as a last cache for secondary storagesecondary storage

17. A logical extension in which CPU switches jobs so 17. A logical extension in which CPU switches jobs so frequently that users can interact with each job while it frequently that users can interact with each job while it is running, creating interactive computing.is running, creating interactive computing.

18. It allows execution of processes not completely in 18. It allows execution of processes not completely in memorymemory

19. A program in execution19. A program in execution

20. It specifies location of next instruction to execute.20. It specifies location of next instruction to execute.

Test 2: Matching TypeTest 2: Matching Type

COLUMN ACOLUMN A COLUMN B COLUMN B

1. Herman Holleriths1. Herman Holleriths a. Operating Systema. Operating System2. Batched Os2. Batched Os b. Consoleb. Console3. Virtual Memory 3. Virtual Memory c. Distributed and Networked OSc. Distributed and Networked OS4. 2nd Generation4. 2nd Generation d. 4th Generationd. 4th Generation5. I/O Manager5. I/O Manager e. Invoker of commandse. Invoker of commands6. User6. User f. Automatic Job Sequencingf. Automatic Job Sequencing7. Routines7. Routines g. System Softwareg. System Software8. Operating System8. Operating System h. 3rd Generationh. 3rd Generation9. Application Program9. Application Program i. Used to solve the computing problemi. Used to solve the computing problem10. WinNT10. WinNT j. Gamesj. Games

k. Punch card machinek. Punch card machinel. Batched processingl. Batched processingm. File and I/O devicesm. File and I/O devicesn. Multi-usingn. Multi-usingo. Build communication o. Build communication

COMPUTATION : (20 points)COMPUTATION : (20 points)Assuming the computer system has the following Assuming the computer system has the following

setup :setup :

If there are 28 instructions, determine the following :If there are 28 instructions, determine the following :

a.) %Eff of CPUa.) %Eff of CPU c.) CR Timec.) CR Time e.) CPU Time in mse.) CPU Time in ms

b.) %Eff of CRb.) %Eff of CR d.) LP Timed.) LP Time

meljun cortes os introduction

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